security issues

[chriszhang-circle]

• backend (FinancialAccountManager):

1. should not use wildcard import when importing libraries
2. API key is sensitive data, should not be allowed to log
3. should not use e.printStackTrace()
4. should not use println
5. should not print out sensitive data like account balance and here as well
6. should not log explicitly about sender and receiver
7. need to use db transaction when move money
8. transfer amount should have input validation, to not allow negative number

• Frontend

1. should write all graphQL for example here in it's own file
2. should keep url in config file instead of hard code
3. api keys is leaked, should use variable in config file instead of hard code
4. API should require authentication https://github.com/j-kopf/nextJSGraphQLapp_sanitized/blob/main/graphql/dataSources.ts#L10-L12